Corrugated paperboard is typically used in many different applications, for example, to form containers, boxes, cartons, or dividers for holding, storing, stacking or shipping various items such as agricultural produce. Recent produce packaging trends have developed for retail markets in open-top retail ready trays (sometimes referred to as tee trays), which allow consumers to purchase various produce items when displayed such open topped containers. Typically, such containers have a bottom and four side walls, and are formed from a blank scored with score lines or cut lines. The blanks are most often formed by automated machines in a continuous in-line process involving cutting, scoring and molding continuous sheets of paperboard. The paperboard is then folded along the score lines or cut lines to form a container. The blanks may be folded into a tray by an automated machine or by a consumer.
During use, containers are often stacked on top of one another for ease of shipping and for optimum use of space. In these circumstances, it is possible for containers to have stacking tabs extending upward from the top edge of the container's side walls. These stacking tabs often fit into corresponding notches cut into an adjacently stacked container to help secure the stack. Since containers are usually stacked on top of like sized containers, the stacking tabs that extend upward from a lower container's side walls position directly into the side walls of a higher, adjacent container. Thus, to accommodate the lower container's tabs, a complimentary notch must be cut out of the higher container's side walls. However, a notch in a side wall is problematic in that it does not secure the stacking tab on all four sides. Thus, these sidewall notches do not fully prevent side-to-side movement, subjecting the stack to potential toppling. This is sometimes circumvented by having a multi-ply side wall, wherein a stacking tab extends upwards from an inner layer of the side wall, thereby aligning the stacking tabs with the bottom panel of an adjacent container as opposed to the side wall. This, however, required excess paperboard to be used to create the multi-layer side wall and related excess costs.
Further, it is easy to misplace a container during stacking such that a higher container falls into a lower container, usually on an angle, potentially damaging the contents of the lower container. To solve this, several prior art containers have devised tapered side walls, wherein the distance between the top edges of the side walls is less than the distance between the lower edges of the side walls. This eases stacking by severely limiting the probability of the higher container falling into a lower container (hereafter, “sub-adjacent container”), since the narrower upper portion creates a more functional ledge for the base of the higher container (hereafter, “super-adjacent container”) to rest on. However, with these containers, the tapered side walls do not have stacking tabs, severely lessening the strength of the stack.
Other prior art containers seek to solve the foregoing problems using fold-down panels or additional side walls or panels that create gussets or corner posts and/or double layer stacking tabs. See, e.g., U.S. Pat. No. 5,860,590 to Blomfield et al., U.S. Pat. No. 6,131,805 to Gasior, and U.S. Pat. No. 6,508,395 to McLeod. However, each has a problem in utilization that makes it relatively unattractive to manufacture or use. For example, some containers require the use of a full-sized panel that requires excessive materials thereby raising costs. Some require complicated procedures to assemble the container. Others require a machine to assemble the container, making such containers expensive to use. Yet others require fasteners such as staples or glue for assembly, which in addition to raising costs, makes it difficult to disassemble the container for storage and re-use without damaging the container. Accordingly, it is a broad object of the present invention to provide a cost-efficient container that is easy to assemble and disassemble and which has multiple features that allow it to be easily stacked with other containers to form a container stack that is stable and which minimizes damages to the containers in the stack.